Indicia applied to articles of clothing and other textiles have become very popular. Fanciful indicia, such as slogans, logos, college names, sports team names and logos, and sayings are commonplace.
Indicia are printed using screen printing machines, with one or more colors. Typically, a screen printing machine has at least one station to print each color. Each station generally includes a printing head, which supports a single screen, the ink, and a mechanism for applying the ink to the textile or substrate. The textile to be printed travels between printing stations. The textile is typically carried by a metal pallet, pallet support, flat bed, or platen. Common printing machines are of the turret-type, or are oval or linear in configuration.
Some printing machines incorporate ink curing stations. Other operations employ separate dryers. A dryer has two primary components: a conveyor system and a heating system. Typically, the drying operation includes an operator setting the internal dryer temperature and the conveying speed to achieve the desired drying characteristics. Commonly known mechanisms are employed to determine or read the ambient temperature in the dryer, which allows the operator to adjust the conveyor speed to compensate to achieve the desired drying.
Numerous inks are available. Such inks include water based inks, sublimation inks, and plastisol. The ink is cured or gelled onto the substrate to a critical temperature. The temperature during the curing process must be kept within a suitable window depending on the ink's curing properties, typically between 125 and 450 degrees Fahrenheit. For example, plastisols must reach a temperature of 320 degrees Fahrenheit. In the ranges below 320 degrees and above 350 degrees, the plastisol will not properly set, resulting in cracking, or it may become liquified. Moreover, if a dye in the textile is overheated, it will migrate, or the textile or substrate may scorch or burn, increasing waste and production costs.
To solve this issue, dryers such as disclosed in U.S. Pat. No. 5,937,535 were developed to sense and control the drying process. Dryers are typically electric or gas-powered, use a great deal of energy, and are essentially a heat sink. Commonly assigned U.S. Patent Publication No. 2014/0047731, which is incorporated herein by reference and made a part hereof, discloses a speed control system for a dryer with an improved belt control system that reduces the amount of energy the dryer uses on startup, thereby reducing energy consumed in the drying process, and cutting costs of operation.
Another challenge in using dryers is the manner of making a belt track through the use of crowned rollers and skewing the belt in one direction or another by adjusting bolts until the belt is centered. This manner requires frequent adjustments and readjustments, and can also result in the edges of belts being destroyed because the belt fell out of proper alignment requiring belt replacement. Some belt tracking systems in current use are provided in the dryer tunnel which has the undesired effect of reducing the useable width of the belt ultimately reducing throughput. In one preferred form of the invention, the dryer is a textile dryer, but could be a dryer for other items.
Applicant, M&R Printing Equipment, Inc.'s, Glen Ellyn, Ill., line of dryers, more particularly conveyor dryers, and even more particularly conveyor dryers for textiles. Suitable dryers include infrared electric textile dryers and propane and natural gas conveyor dryers. M&R has designed and manufactured several dryers, the TRANSFORMER™, BLU-FLASH™, FUSION™, RADICURE™, Sprint 3000, Vitran systems. Belt width similarly can vary. Common widths are between 24″ to 87″ and conveyer lengths ranging from about 82″ or longer.